Water Requirements for Irrigation

Select To Calculate

Select a Reference Crop:

ETref

ETc

IWR

Alfalfa

Grass

 

Select ETref Model (s)


General Penman-Monteith model  

Alfalfa

Standardized ASCE Penman Monteith Model  
Original Penman Model  
Kimberly 1982 Penman Model  
Jensen-Haise Method  
 
Enter The Adjusted Number To Grass

Grass

FA-O56 Penman Monteith Model  
FAO-24 Penman Model  
Turc 1961 Method  
FAO Blaney-Criddle Method  
Hargreaves 1985 Method  
FAO-24 PAN Evaporation Calculation  
 
Enter The Adjusted Number To Alfalfa

Data Entery Methods

From Keyboard
From File
From Server Data Base
Model

Model (1)

General Penman-Monteith model

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

%

RHmax

Max

Relative Humidity

%

RHmin

Min

m/s

Uz

Wind Speed

m

zw

Height Of Wind Measurement Above Ground Surface

hour

n

Actual Duration Of Sunshine In A Day

cm

hcref

Crop Height

-

J

Number Of Day In The Year

m

E

Elevation

LAT

Latitude

MJm-2day-1

Rn

Net Radiation

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (2)

Standardized ASCE Penman Monteith model

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

%

RHmax

Max

Relative Humidity

%

RHmin

Min

m/s

Uz

Wind Speed

m

zw

Height Of Wind Measurement Above Ground Surface

hour

n

Actual Duration Of Sunshine In A Day

-

J

Number Of Day In The Year

m

E

Elevation

LAT

Latitude

MJm-2day-1

Rn

Net Radiation

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (3)

Original Penman Model

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

%

RHmax

Max

Relative Humidity

%

RHmin

Min

m/s

Uz

Wind Speed

m

zw

Height Of Wind Measurement Above Ground Surface

hour

n

Actual Duration Of Sunshine In A Day

-

J

Number Of Day In The Year

m

E

Elevation

LAT

Latitude

MJm-2day-1

Rn

Net Radiation

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (4)

Kimberly-Penman 1982

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

%

RHmax

Max

Relative Humidity

%

RHmin

Min

m/s

Uz

Wind Speed

m

zw

Height Of Wind Measurement Above Ground Surface

hour

n

Actual Duration Of Sunshine In A Day

-

J

Number Of Day In The Year

m

E

Elevation

LAT

Latitude

MJm-2day-1

Rn

Net Radiation

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (5)

Jensen-Haise Method

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

-

J

Number Of Day In The Year

m

E

Elevation

LAT

Latitude

MJm-2day-1

*Rn

Net Radiation

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (6)

FAO-56 Penman Monteith Model

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

%

RHmax

Max

Relative Humidity

%

RHmin

Min

m/s

Uz

Wind Speed

m

zw

Height Of Wind Measurement Above Ground Surface

hour

n

Actual Duration Of Sunshine In A Day

-

J

Number Of Day In The Year

m

E

Elevation

LAT

Latitude

MJm-2day-1

Rn

Net Radiation

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (7)

FAO-24 Penman Model

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

%

RHmax

Max

Relative Humidity

%

RHmin

Min

m/s

Uz

Wind Speed

m

zw

Height Of Wind Measurement Above Ground Surface

hour

n

Actual Duration Of Sunshine In A Day

-

J

Number Of Day In The Year

m

E

Elevation

LAT

Latitude

MJm-2day-1

Rn

Net Radiation

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (8)

 

 

Turc 1961 Method

 

 


 

 

The Required Data

 

 

 

Ta

Average Air Temperature

%

RHa

Average Relative Humidity

hour

n

Actual Duration Of Sunshine In A Day

-

J

Number Of Day In The Year

LAT

Latitude

MJm-2day-1

Rs

Solar Or Short Wave Radiation

Model (9)

 

 

FAO Blaney-Criddle Method

 

 

The Required Data

 

 

 

Ta

Average Air Temperature

%

RHa

Average Relative Humidity

hour

n

Actual Duration Of Sunshine In A Day

-

J

Number Of Day In The Year

LAT

Latitude

MJm-2day-1

Rs

Solar Or Short Wave Radiation

m/s

Ud

Daytime Wind Speed

-

p

Mean Daily Percent of Annual Daytime Hours

Model (10)

 

 

Hargreaves 1985 Model

 

 

The Required Data

 

 

 

Tmax

Max

Air Temperature

Tmin

Min

Ta

Average

Model (11)

 

 

FAO-24 PAN Evaporation

 

 

The Required Data

 

 

 

%

RHa

Average Relative Humidity

m/s

Uz

Wind Speed

m

zw

Height Of Wind Measurement Above Ground Surface

mm/day

Epan

Pan Evaporation

m

Fetch

Distance Of The Identified Surface Type

Counter

King Saud University - Alamoudi Water Chair
Dr. A .A. Alazba & Eng. N. A. Alrdyan